Aluminum-base greases



Patented Dec. 2, 1947 ALUMINUM-BASE GREASES Francis Joseph Licata, New York, N. Y., assignor to Nopco Chemical Company, Harrison, N. J a corporation of New Jersey NoDrawing. Application August 14, 1942,

Serial No. 454,825

Claims. (Cl. 25236) This invention relates to improved aluminumbase greases.

Aluminum-base greases ar widely used for lubrication purposes, because of their waterproof characteristics, their heat-resistance within certain limitations,- and their attractive appearance. Howeventhese greases have certain disadvantages, notably their tendency to assume a jellylike, rubbery texture upon heating above a certain critical temperature; their tendency towards syneresis, or bleeding out of oil in storage and use; and their somewhat granular and crumbling structure. Further, the oils contained in aluminum-base greases must be of relatively high viscosity in order to form a stable grease.

Accordingly, it is an object of this invention to provide aluminum-base greases which will have a smooth, unctuous and greasy texture, and which will retain this texture, when heated to elevated temperatures: 4'

Another object is to provide an aluminum-base grease which will notsepa rate. oil upon standing.

Still another object is to provide an aluminumbase grease in which a largerproportion of soap base may be incorporated than has hitherto been possible.

The above and other objects are attained by this invention in aluminum-base greases which contain, in addition to aluminum soaps of saturated higher fatty acids, a small proportion of a lithium soap of a higher fatty acid. The added lithium soap serves to stabilize the colloidal structure of the grease, preventing syneresis thereof during storage and use, and restraining the tendency of the grease to assume a rubbery texture at high temperatures. Further, greases prepared according to this invention are characterized by having a smoother and more unctuous texture in comparison to aluminum-base greases heretofore prepared, and likewise are capable of holding a substantially greater amount of soap for a given consistency than is possible with aluminum-base greases heretofore prepared. The expressions aluminum-base greases and aluminum soaps as used herein are qualified in that, in each instance, the aluminum base or soap is that of an aluminum soap of a saturated higher fatty acid.

Except for the nonaluminum soap additive just mentioned, the greases of this invention will be constituted substantially the same as the aluminum-base greases hitherto manufactured, containing in general between about 2% and about 15% to 20 of aluminum soaps of saturated higher fatty acids, the balance comprising essentially lubricating oils. The percentage of aluminum soap incorporated into the greases of this invention may be slightly higher than in the usual aluminum-base greases, in view of the softening tendency of the nonaluminum soap additive. The aluminum content of the aluminum soap may be varied between the usual limits and will generally be such that the washed ash determined upon the soap will lie between about 4% and about 12%. The fatty residues in the aluminum soap may be of the types customarily used in aluminum-base greases, i. e. higher saturated fatty radicals on the order of palmitic, stearic, margaric, etc. radicals.

The fatty'radicals in the lithium soap may be any of the higher fatty acids having molecules containing upwards of 8 carbon atoms, and preferably upwards of 16 carbon atoms. Preferably,

but not necessarily, the fatty acids should be saturated. A list of suitable fatty acids, the lithium soaps of which may suitably be employed in the greases of this invention, includes palmltic stearic, arachidic, lauric, margaric, oleic, elaidic, erucic and the like fatty acids. Instead of the soaps of pure fatty acids, there may be employed soaps of suitable mixed fatty radicals coming within the requirements above set forth, such as the mixed fatty radicals derivable from the animal and vegetable oils, fats and waxes such as tallow, corn oil, cottonseed oil, hydrogenated fish oils and the like. Likewise, the naphthenic acids are suitable components of the nonaluminum soaps incorporated into greases according to this invention. The mol-ratio of metallic and of fatty radicals present in the said soaps may vary: in general, at least one of the valencies of the metal should be combined with fatty radicals, but a higher ratio may desirably be employed. Usually, the neutral soap will be employed.

The amount of lithium soap incorporated into the grease of this invention may vary, depending on the properties desired in the final product, but in general this amount will be only a small fraction of the amount of the aluminum soap present. Roughly, the objects of this invention may be attained by the addition of from about 0.1% to about 5% of the lithium soap, based upon the total weight of grease. In general, the higher the percentage of lithium soap, the softer the resulting grease will be for any given percentage of aluminum soap, and advantage may be taken of this fact to add a considerably greater total amount of soaps to the grease than has heretofore been possible with aluminum-base soaps,

The manner of preparing greases of this invention may follow any conventional practice,

this not being critical to the invention. Conveniently, the aluminum soap, lithium soap, lubricating oil and any other desired ingredients may be mixed and heated to a temperature sufficiently high to effect homogeneous blending thereof. Thereafter the product may be cooled and packaged for use.

Aluminum-base greases prepared according to this invention are compatible with all the usual additives and modifying agents, such as latex, alkylated aromatics, etc., customarily added to such greases, and are improved and modified in the usual respects by such additives.

With the above discussion in mind, there is given herewith an example of a grease prepared in accordance with this invention. All parts given are by weight.

Example Parts Aluminum stearate (8% washed ash) 11 Lithium soap (neutral stearate) 1 Paraflin oil (100 sec. viscosity at 100 F.) 88

The above ingredients were heated to 150 C. with stirring, and slowly cooled to room temperature. The resulting grease was soft with a smooth texture and free from bleeding. On reheating, it melted without passing through the rubbery stage.

From the above, it will be seen that the greases provided by this invention are distinguished from similar greases heretofore prepared in that they do not become rubbery upon heating. This is highly advantageous, since the greases do not lose their lubricating properties upon overheating of the surfaces to which they are applied. Further, greases according to this invention possess a smoother and more unctuous texture than aluminum-base greases heretofore prepared. Still further, the greases of this invention may have a higher net soap content, may be made from less viscous oils without danger of bleeding out of the oil, and exhibit a higher degree of water-resistance than aluminum-base 4 greases of the prior art. Finally, greases according to this invention are highly stable, in storage and use, against any separation or syneresis of the oils contained therein.

I therefore, claim:

1. A lubricating grease comprising mineral oil, 2% to 20% of an aluminum soap of a saturated higher fatty acid and 0.1% to 5.0% of a lithium soap of a higher fatty acid, the quantity of lithium soap being only a fraction of that of the aluminum soap present.

2. A lubricating grease comprising mineral oil, 2% to 20% of an aluminum soap of a saturated higher fatty acid and 0.1% to 5.0% of a lithium soap of a saturated higher fatty acid, the quantity of lithium soap being only a fraction of that of the aluminum soap present.

3. A lubricating grease comprising mineral oil, 2% to 20% aluminum stearate and 0.1% to 5.0% of a lithium soap of a higher fatty acid, the quantity of lithium soap being only a fraction of that of the aluminum soap present.

4. A lubricating grease comprising mineral oil, 2% to 20% aluminum stearate and 0.1% to 5.0% of a lithium soap of a saturated higher fatty acid, the quantity of lithium soap being only a fraction of that of the aluminum soap present.

5. A lubricating grease comprising mineral oil, 2% to 20% aluminum stearate and 0.1% to 5.0% lithium stearate, the quantity of lithium soap being only a fraction of that of the aluminum soap present.

FRANCIS J. LICATA.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,625,969 Willock et a1. Apr. 26, 1927 1,860,622 Rosenbaum May 31, 1932 2,266,544 Freuler Dec. 16, 1941 2,332,247 Morway et al Oct. 19, 1943 2,390,450 Morgan Dec. 4, 1945 

